#define _CRT_SECURE_NO_WARNINGS 1
#include<iostream>
using namespace std;
int main()
{
	double s;
	cin >> s;
	int cnt = 0;
	double sum = 0;
	double k = 2;
	int i = 0;
	while (sum < s)
	{
		sum += k;
		i++;
		if (sum >= s) break;
		k = 0.98 * k;
	}
	cout << i << endl;
	return 0;
}